To enable the use of sunglass lenses with spectacles having prescription lenses, various forms of "clip-on" detachable auxiliary spectacle frames have been proposed which allow the auxiliary frame housing sunglass lenses to be clipped onto the frame front of the primary spectacle frame housing the prescription lenses via various forms of clips. The success of the various forms of clips varies in terms of security of attachment, non-intrusive appearance and ease of attachment/detachment.
Replacement of the clip type attachment means with cooperating magnetic attachments on both the primary and auxiliary spectacle frames has also been proposed. The security of attachment of currently available spectacle frame assemblies of this type is quite poor, however, with the auxiliary spectacle frame typically being free to rattle, vibrate or flicker and possibly disengage with any jarring movements of the wearer, such as during various forms of exercise. Rattling, vibrating or flickering of the auxiliary spectacle frame can be uncomfortable and possibly harmful to the human eye by causing optical distortion as well as rapid variations in light levels if light is able to pass around the tinted lenses of the auxiliary spectacle frames when displaced.